.NET C# USB library for WinUSB, LibUsb-Win32, and libusb-1.0. Using the common device classes, applications work with all operating systems and drivers without modification. Lots of example code. Open source software at sourceforge.net.

A multi-platform software synthesiser emulating (somewhat inaccurately) pre-GM MIDI devices such as the Roland MT-32, CM-32L, CM-64 and LAPC-I. In no way endorsed by or affiliated with Roland Corp. Source hosted at: http://www.github.com/munt/

GLibWMI is a Component Library for Delphi that encapsulate the classes for access to WMI of Windows in a set of VCL. BiosInfo, PrinterInfo, DiskInfo,... Allow access WMI Classes: WIN32_Bios, WIN32_Printers, WIN32_DiskDrive. Simple, Drop and Active it

Famous mpg123 lightweight .net wrapper with sample. For use in your own .net mp3 projects. Read ID3 tags, decoder MP3 files, play them out. Really fast decoder for your managed applications. Written in .net 2.0 and c#.
It is used in production environment for real-time decoding of audio stream data for http://www.videophill.com/index.php?page=streamsink

A library for drawing 2D primitive shapes in XNA. The library has methods for drawing pixels, lines, rectangles, filled rectangles, circles, and arcs.
Development moved to: https://bitbucket.org/C3/2d-xna-primitives